Template images for nonhuman primate neuroimaging: 1. Baboon

Coregistration of functional brain images across many subjects offers sever al experimental advantages and is widely used for studies in humans. Voxel- based coregistration methods require a high-quality 3-D template image, pre ferably one that corresponds to a published atlas. Template images are avai lable for human, but we could not find an appropriate template for neuroima ging studies in baboon. Here we describe the formation of a T1-weighted str uctural MR template image and a PET blood flow template, derived from 9 and 7 baboons, respectively. Custom software aligns individual MR images to th e MRI template; human supervision is needed only to initially estimate any gross rotational misalignment. In these aligned individual images, internal subcortical fiducial points correspond closely to a photomicrographic babo on atlas with an average error of 1.53 mm. Cortical test points showed a me an error of 1.99 min compared to the mean location for each point. Alignmen t of individual PET blood flow images directly to the PET template was comp ared to a two-step alignment process via each subject's MR image. The two t ransformations were identical within 0.41 mm, 0.54 degrees, and 1.0% (trans lation, rotation, and linear stretch; mean). These quantities provide a che ck on the validity of the alignment software as well as of the template ima ges. The baboon structural AIR and blood flow PET templates are available o n the Internet (purl.org/net/kbmd/b2k) and can be used as targets for any i mage registration software. (C) 2001 Academic Press.